1. Field of the Invention
The present invention relates to a numerical controller and, in particular, to a numerical controller that has an automatic trace function of a related signal in association with an NC program operation.
2. Description of the Related Art
When an interpolation function or an auxiliary function of an NC program is executed, a function of outputting a particular signal (F signal) with respect to a programmable controller is available. A ladder program periodically executed in a programmable controller processes a signal from an NC and outputs a signal to the outside. Furthermore, interpolation functions and auxiliary functions of an NC program include a function of requesting a completion signal (G signal) from a programmable controller.
An operator may use a trace function with respect to the flow of a series of processing of these signals to perform debug or maintenance work of a ladder program. However, in order to find out a group of these related signals, it is necessary to check in advance related input and output signals of each of interpolation functions and auxiliary functions. Furthermore, in order to check a signal influenced by the related input and output signals of each of interpolation functions and auxiliary functions in the ladder program, it is necessary to use a cross reference function or the like to search for a signal in a dependent relation therewith.
As prior art techniques for checking a signal in a dependent relation more easily, the following functions are publicly known: a function with which, when a command that forms a ladder program is selected, cross reference information of a signal used in the command is automatically displayed (for example, Japanese Patent Application Laid-Open No. 10-293603) and a function with which a dependent relation of signals within a ladder program is automatically extracted (for example, Japanese Patent No. 5362148).
However, in order to debug the processing flow of a signal output when an interpolation function or an auxiliary function of an NC program is executed and a signal related to that signal as well as the processing flow of a signal requested by the interpolation function or the auxiliary function and a signal influenced by that signal, or in order to check for maintenance work, signals related to various functions of the NC program has to be checked in advance, and a signal influenced by that signal in a ladder program has to be checked. These procedures require considerable efforts.